Lignin derivative

ABSTRACT

Lignin derivatives, particularly for use in oil base drilling muds, are obtained by reacting an oxidized lignin with an amine to form a salt and heating the resulting salt to elevated temperatures until a substantial portion of the product is converted to a nitrogen containing product wherein the nitrogen is stable in an aqueous alkaline medium at room temperature.

ited States Patent Kim 1 *June 20, 1972 54 LIGNIN DERIVATIVE [56]References Cited [72] Inventor: Chung Sur Youn Kim, Sacramento, Calif.UNITED STATES PATENTS [7 1 Assigneer Georgia-Pacific Corporation,Portland, 2,935,504 5/1960 King et al ..252/s.5 x Oreg. 3,232,870 2/1966Cowan et al. ..252/8.5

[ Notice: The portion of the term of this patent sub- 1 scqufim to Jun27 I987. has been my claimed.

Primary Examiner-Herbert B. Guynn [22] 1970 Attorney--Peter P. Chevis[21] Appl. No.: 13,186

Related U.S. Application Data Division of Ser. No. 629,894, April 11,1967, Pat. No. 3,538,071.

U.S. Cl ..252/8.5 M, 252/8.5 P, 252/353, 252/354, 252/355, 252/356,252/357, 260/124 R, 260/124 A Int. Cl ..C10m l/40, C10m 1/32 Field ofSearch ..252/8.5 M, 8.5 P, 353, 354,

[ 57] ABSTRACT 14 Claims, No Drawings LIGNIN DERIVATIVE This applicationis a divisional application of application Ser. No. 629,894, filed Apr.1 l, 1967, now U.S. Pat. No. 3,538,071.

Lignin is a polymeric substance of substituted aromatics found in plantand vegetable tissue associated with cellulose and other plantconstituents. In the pulp and paper industry, lignin-containingmaterials such as wood, straw, corn stalks, bagasse, and other vegetableand plant tissues are processed to recover the cellulose or pulp withthe lignin being obtained as a by-product. Since vegetable and planttissues generally contain an appreciable portion of lignin, a largeamount is available. While considerable effort has been expended to findways to utilize more fully the chemical values of lignin, only limitedmarkets for lignin have been developed. Sulfonated lignincontainingmaterials have been used in relatively a small field of application asdispersing agents and for the preparation of drilling mud additives.While the sulfonated lignin-containing material drilling mud additiveshave been used in both oil base and water base drilling fluids, theirmost extensive use has been limited to water base fluids. Oil basedrilling fluids, particularly water-in-oil emulsion type muds, havecharacteristics which in some respects make them superior to water basedrilling fluids. especially for deeper wells in which the conditions aremore drastic and demanding.

It is, therefore, an object of this invention to provide a ligninderivative having improved surface active properties. Another object isto provide a nitrogen-containing lignin derivative and a process for itspreparation. A still further object is to provide a lignin derivative,especially effective as an additive in waterin-oil emulsion drillingfluids and compositions thereof.

The above and other objects are attained by intermixing the polymericconstituents of an oxidized lignin product with a primary or secondaryamine having substituents of from six to 30 carbon atoms to interact theamine with the lignin derivative and heating the reaction product.

The composition thus obtained has improved surface active properties.The compositions are especially useful as a drilling fluid additive,particularly for water-in-oil type emulsions where they function asfluid loss and emulsifying agents. As drilling fluid additives they havehigh temperature stability and do not lose their eficctiveness in thepresence of strong alkali or contaminants.

Lignin obtained by any method or from any source may be oxidized andused in the preparation of the compounds of this invention. While thereis some variation in the chemical structure of lignin products,depending upon the plant from which the lignin is obtained, place wherethe plant is grown, and also upon the method used in the recovery orisolation of the lignin from the plant tissue, the basic structure andproperties of the lignin are similar with the variations beingunimportant for the current purpose. The molecular weight of the monomeror the building unit making up the large polymer of lignin has not beendefinitely determined but is considered by many in the industry to beabout 840. A unit of this size has been considered to be necessary toobtain the basic chemical properties of lignin. The lignin productsobtained from plant tissue by a normal pulping process such as thesulfite pulping process contain lignin molecules of varying size fromone or several building units up to well in the hundred thousandsmolecular weight.

As with any high molecular weight polymeric material, the results ofmolecular weight determinations of lignin vary somewhat depending uponthe method employed for the determination. The method used herein forthe determination of molecular weight is the agar gel diffusion methodas developed and described by J. Moacanin, H. Nelson, E. Beck, V. F.Felicctta and J. L. McCarthey in J. Am. Chem. Soc. 81, 2054 1959).

Since lignin is found associated with cellulosic materials in vegetableand plant tissue, one of the main sources of lignin is the residualpulping liquor obtained in the pulp and paper industry wherelignocellulosic materials are processed to recover the cellulose orpulp. The lignin as obtained by separation of the cellulosicconstituents from the plant may be chemically altered somewhat and notas it is found in the plant. Thus, the term lignin product as usedherein means the lignin product which is obtained upon separation fromthe cellulose or recovered from the plant. in the sulfite pulpingprocess, the lignocellulosic material is digested with a bisulfite orsulfite resulting in the sulfonation of the lignin. In other methods ofrecovery or separation of the lignin from the plant, the lignin may notbe sulfonated but may be chemically altered somewhat in some othermanner. For example, residual pulping liquors obtained in the sulfateprocess or kraft process (as well as alkali lignin obtained from thepulping of lignocellulosic materials by other alkaline processes) maycontain the lignin as some alkali metal compound and maybe partiallyoxidized. Hydrolysis lignin obtained from the hydrolysis of thelignocellulosic materials in the manufacture of wood sugars and"hydrotropic lignin" derived from the hydrotropic pulping process maylikewise have the lignin altered somewhat from that found in the plant.However, the basic polymeric lignin structure is present which uponoxidation will give basically the same or similar degradation productsand thus are operative. Also, the lignin products such as a residualpulping liquor may be subjected to various treatments such as, forexample, acid, alkaline, or heat treatments or reaction with otherchemicals which may further alter somewhat the lignin constituents. Thelignins remain operative as long as the treatment is not so severe as todestroy the basic polymeric structure of the lignin or condensed to anexcessively higher molecular weight.

The term polymeric constituents, as used herein, means the water solublehigh molecular weight constituents, ranging in molecular weight from thehigh molecular weight components which are just soluble in water down tothose having a diffusion of about 25 mm /day, recovered from an oxidizedlignin.

The residual pulping liquors or the lignin-containing product obtainedin the separation or recovery of the lignin from the plant may containmany other constituents besides the lignin. For example, in the sulfitepulping process, the spent sulfite liquor contains lignosulfonate whichmay be present as salts of certain cations such as magnesium, calcium,ammonium, sodium and others which may have been present during thesulfonation of the lignin. The spent sulflte liquor generally containsonly about 40 to 60 Weight percent of lignosulfonate with the remainderbeing carbohydrates and other organic and inorganic constituentsdissolved in the liquor. Lignin products obtained by other pulpingprocesses may likewise contain other materials such as carbohydrates,degradation products of carbohydrates and resinous materials which areseparated from the lignocellulosic materials with the lignin. Ligninobtained by hydrolysis of the lignocellulosic materials may not containthe carbohydrate but may contain resinous type materials as well asother materials which were not removed by the hydrolysis. It is notnecessary to separate the lignin-containing constituents from the otherconstituents. The lignin product as obtained with all constituents maybe oxidized or the liquors may be subjected to difierent treatments suchas, for example, alkaline, acid or heat treatments, as well as reactedwith chemicals to modify or remove some of the constituents prior tooxidation.

The term oxidized lignin, as used herein in reference to lignin, meanssubjecting the lignin product to oxidation to the extent that theoxidized lignin product has a carboxyl radical content, expressed asCOOH, of at least 8 weight percent.

In oxidizing the lignin product, the various known methodsof oxidationmay be used. Lignins are very susceptible to oxidation and appreciableoxidation of the lignin molecule is obtained even under relatively moldoxidizing conditions. The oxidation may be carried out under acid,neutral or alkaline conditions and with various oxidizing agents.Illustrative examples are oxidizing agents such as oxygen, air, ozone,peroxides, halogens, halogen oxides, permanganates, chlorites,

hypochlorites, chlorates, chromates, metal oxides such as oxides ofcopper, silver, cobalt, mercury and lead, mineral acids such as nitric,oxides of nitrogen and organic oxidizing agents such as nitrobenzene,nitromethane, peracetic acid, and nitrotoluene. Heating of the ligninunder alkaline conditions such as obtained in a kraft pulping processmay be sufficient to oxidize the lignin to be operative. In addition tousing chemical oxidizing agents, other means such as electrolysis orenzymatic oxidation may also be used. The oxidation may be carried outunder relatively low temperatures but temperatures up to 180 C are oftenused and temperatures up to 210 C or higher may be used depending uponthe oxidizing agent or method employed. Catalysts may also be used, forexample, metal oxides.

The oxidation is carried out to the extent that the oxidized ligninproduct will contain at least 8 percent, preferably at least 10 percent,of carboxylic radicals, calculated as the carboxylic acid groups, asdetermined by conductometric titration. While in the oxidation somecarboxylic acid groups may be introduced into the polymericconstituents, it is believed that other reactions are effected due tothe oxidation which are largely responsible for the effectiveness of theproductv Lignin contains hydroxyl and methoxyl substituents which uponoxidation result in the formation of various types of polymericcompounds and lower molecular weight compounds such as vanillin andother aromatic products. Since the lignin products generally containmany other constituents besides lignin, for example, carbohydrates, manyofthese constituents are possibly converted to relatively low molecularweight acids which are later on separated from the polymericconstituents. Thus, the carboxyl content the lignin oxidation productdoes not necessarily indicate the carboxyl content of the polymericconstituent, but is only indicative of the oxidation to obtain theeffective products. The lignin product can be oxidized to the extentthat only a small amount of high molecular weight of polymericconstituents remain. However, for practical purposes, continuing theoxidation decreases the yield of polymeric constituents so that theoxidation generally is not continued beyond the point where the carboxylradical content, expressed as COOH, is over 35 weight percent of theoxidized product.

The polymeric constituents may be recovered from the resulting oxidizedproduct prior to the reaction with the amine and heating. Since thepolymeric constituents are the high molecular weight constituents, theygenerally form amine salts which have limited solubility in an aqueousmedium. Thus, the separation may be made by the addition to the oxidizedproduct of the desired primary or secondary amine to precipitate theseconstituents. The amine salt thus obtained can be heated to obtain thedesired product. However, this means of isolation is not necessary. Thepolymeric constituents can be recovered by other known methods, forexample, by dialysis, electrodialysis, ion exchange, or acidprecipitation as well as solvent extraction. Also, for the separation ofthe polymeric constituents by precipitation of the amine salt, it is notnecessary to use the primary or secondary amine desired in the finalproduct. Tertiary amines may be used which will form amine salts havinga limited solubility. However, after the salts are recovered withtertiary amines, the amine salts have to be reacted with a base and anacid or other means used to convert the polymeric constituents to theacid form and then reacted with the primary or secondary amine to obtainthe desired amine salt to be subjected to heating. Thus, generally, theoxidized product is intermixed with the amine and the amine salt of thepolymeric constituents is precipitated. or extracted with organicsolvent, if it does not have the necessary limited solubility toprecipitate. Solvents such as chloroform, butanol, benzene,perchlorethylene, xylene and toluene may be used. Also, depending uponthe method of recovery used, some of the lower molecular weightdegradation products may also be recovered which may react with thedesired amine. Generally these products, including the sugar degradationproducts, have some effectiveness so that their presence is notnecessarily detrimental.

While the recovered polymeric constituents may contain carboxyl radicalsor other constituents containing carboxyl radicals may be recovered withthe polymeric constituents which radicals may react with the amine toform an amine salt, it is believed that the amine also reacts with otherfunctional groups in the polymeric constituents. Upon heating thereaction product of the amine and the polymeric constituents, theproduct obtained is substantially insoluble in an aqueous alkalinemedium. The nitrogen in the product is likewise stabilized by theheating in that it is not readily removed from the heated product by analkali in an aqueous medium at room temperatures.

Usually the polymeric constituent mixture or reaction product is heatedat a temperature from about l20 C to just below the thermaldecomposition temperature of the product such as a charring temperature.A temperature in the range of to 185 C is preferred, and it is seldomthat temperatures above 200 C are employed. The time the reactionproduct must be subjected to the high temperature will vary with thetemperature employed. At the higher temperatures, 5 to l0 minutes orjust the time necessary to heat the mixture to a high temperature may besufiicient, while at lower temperatures it may be desirable to maintainthe product at the low temperature for l to 2 days. At the preferredtemperature of l45 to 185 C, generally the product is heated from aboutto 16 hours.

Upon heating, the emulsification properties of the product improve forwater-in-oil emulsions, especially when used under highly alkalineconditions under which many emulsifiers are ineffective. Usually whenthe products are to be used as emulsifiers for water-in-oil emulsion,the products are heated to the extent that the voltage required to breakdown the emulsion made with these products is at least 120 volts.

A further change noted as the result of the heating is an increase inthe solubility of the product in diesel oil. For some of the products, asubstantial portion of the amine reaction product may not be soluble inoil and may be separated from the oil by centrifugation. For example, amajor portion of an amine reaction product prepared from a spent sulfiteliquor which has been subjected to moderate oxidation by heating and airblowing may be, after drying, insoluble in oil. However, if the aminereaction product is heated, for example at C, it is converted to aproduct which is soluble in diesel oil. The amount of material separatedby centrifugation decreases with heating to the amount of the inorganiccompounds expected to be found in the product as the result of itspreparation which have not been removed. Generally, the amine reactionproduct is heated until the major portion or at least 50 percent is oilsoluble.

in heating the polymeric constituent-amine product, preferably dryingconditions are maintained. This does not mean that the conditions haveto be anhydrous but that the moisture content is maintained sufficientlylow in the reaction to favor a dehydrating reaction. This may beaccomplished, for example, by mixing the polymeric constituents andamine in dry form and heating, or by heating the polymericconstituent-amine product precipitate as recovered from the reactionmixture by filtration or centrifugation at atmospheric pressure, orheating the polymeric constituent-amine product in a solvent which formsan azeotrope with water or otherwise having the water distilled off onheating.

The heating is also usually carried out at a pH of at least 4.5,preferably at a pH in the range of 6 to 9 or up to the pH of thereacting amine. The desired pH can be obtained by various methods. Forexample, the pH of the polymeric constituents can be lowered justsufi'tciently so that upon the addition of the amine the desired pH isobtained in the reaction mixture. However, the pH may also be adjustedby use of an amine or the addition of a small amount of an inorganicalkali to the reaction mixture or the amine of alkali intermixed withthe reaction product during heating.

The primary and secondary amines which may be used are alkyl and arylprimary and secondary amines having substituents of from six to 30carbon atoms. Amines having from 12 to carbon atoms are preferred.Saturated and unsaturated amines may be used, including aryl amines.Illustrative examples are cyclohexanolethylamine, benzylethanolamine,fatty amines, purified or mixed, dodecylamine and dioctylamine.

The ratio of the amine intermixed is generally such that the nitrogencontent, which is stable to alkali at room temperature in the heatedproduct, represents an amount of the amine in the range of from 70 to100 percent of the polymeric constituents. However, the amount of amineused may be as little as 35 percent of the polymeric constituents or upto 150 percent or more.

Characteristics and properties of the products may be varied somewhat bythe variation of the degree of oxidation of the lignin as well as thechoice of amine used in the formation of the product. Alkylamines havingfrom about 12 to 20 carbon atoms will result in products having a goodstability in oil and thus make preferred emulsifiers for water-in-oilemulsions. Generally the most effective additives for use in oil basedrilling muds are obtained with polymeric constituents having adiffusion coefficient in the range of 8 to 20 mm lday.

When the product is used in oil base muds, the amount added can bewidely varied from about 1.5 to 50 lbs per bar rel. The products alsohave fluid loss properties and will appreciably decrease the fluid lossat concentrations above about 2 or 3 lbs/barrel. Other materials, suchas weighting materials, clay. and other additives, usually used in theoil base drilling fluid may be also used in conjunction with theadditrve.

EXAMPLE 1 An oxidized calcium base fermented spent sulfite liquor wasused in the preparation ofa fatty acid lignin derivative.

A fermented calcium base spent sulfite liquor was oxidized in thepreparation of vanillin. After recovery of vanillin, the high molecularweight constituents were precipitated from the a ueous solution byslowly adding concentrated hydrochloric acid to the oxidized productuntil the pH of the solution became l to 2. The acid treated solutionwas filtered to recover the precipitated polymeric constituents whichhad a diffusion coefficient of about 19 mm' /day and carboxylic acidcontent of about 1 1 percent as determined by conductometric titration.

The polymeric constituents in an amount of 50 g were intermixed with 40g of commercial fatty amine mixture in 400 ml of toluene. The mixture ofthe amine with high molecular weight lignin constituents was placed in abomb and agitated at 135 C for 20 hours, after which the toluene wasevaporated to obtain the lignin derivative as a residue. The product wasdried and pulverized by a Waring blender and weighed 85 g. The analysisand properties of the lignin derivative compared to that of the reactantare shown in the table below.

Lignin lsolated as To illustrate the surface active properties of thelignin derivative, the product was tested as an emulsifier forwaterin-oil systems. The derivative in an amount of 10 g was intermixedwith 200 ml of diesel oil and about 1 g of sodium hydroxide as a 25weight percent solution. Saturated salt brine in an amount of 150 ml wasslowly added and the mixture was vigorously mixed for 20 minutes. Theemulsion obtained at this point was stable and a voltage of 180 voltswas required to obtain a current flow through the emulsion as tested bya Farm Emulsion Tester. Further additions of brine were made while theemulsion was mixed until a phase inversion or coagulation of thewater-in-oil emulsion occurred. Fourteen hundred milliliters of brinewere added before the phase inversion was ob tained indicating that thelignin derivative was a good waterin-oil emulsifier. Under the abovetests, emulsifiers which permit the addition of 1.000 ml or more ofsaturated brine before a phase inversion are considered to be goodemulsifiers.

EXAMPLE 11 An oxidized spent sulfite liquor obtained upon the oxidationof the liquor in preparation of vanillin similar to that described inExample 1 was used in the preparation of an n-hexylamine derivative.

The polymeric constituents of the degraded lignin were precipitated fromthe vanillin raffinate by addition of hydrochloric acid until a pH of lwas obtained. The precipitated lignin constituents were recovered bycentrifugation. The soluble portion of the raffinate was extracted withhexylamine to recover minor amounts of degraded lignin constituentswhich had failed to precipitate.

The amine extract and the precipitate were sealed in a bomb with anadditional 70 m1 of hexylamine. The bomb was agitated and heatedovernight at a temperature of about 130 C.

The reaction product was washed with hydrochloric acid solution having apH of 1. After the acid wash, the hexylamine derivative was dissolved ina 5 weight percent sodium hydroxide solution and the unreacted amineremoved by contacting the solution with ether to extract the amine andother ether soluble constituents. The solution was then neutralized to apH of 6.5, precipitating the hexylamine derivative.

EXAMPLE [11 A nitrogen-containing lignin derivative was prepared from anoxidized spent sulfite liquor.

A fennented calcium base spent sulfite liquor was oxidized by bubblingchlorine slowly into spent sulfite liquor solution at 20 C. Thechlorination of the lignosulfonate continued precipitating the highermolecular weight constituents. The precipitated constituents, in anamount of 300 g, after washing were dissolved in a 10 weight percentsodium hydroxide solution and heated at to C for 7 hours. The alkalinetreated mixture was then cooled and acidified to a pH of about 1 toprecipitate the polymeric constituents. The precipitated polymericconstituents were washed once with a diluted HCl solution and twice withether and dried at room temperature to yield 151 g. The polymericconstituents had a diffusion coefficient of 8.7 mm lday.

The polymeric constituents in an amount of 50 g were intermixed with 40g of fatty amine mixture and 4 g of isopropylamine in 400 ml of toluene.The reaction mixture was heated overnight with agitation at around C.After the evaporation of the toluene and other volatiles and drying, 85g of the lignin derivative was obtained.

The lignin derivative was tested as an emulsifier for waterin-oilemulsions in a manner similar to that described in Example l and 1.000ml of salt brine were added before the phase inversion was obtained.

The analysis and properties of an oxidized spent sulfite liquor and ofthe lignin derivative are shown in the table below.

Deriv- Analysis ative 7c N (Kjeldahl) 0.0 0.0 2.9 Methoxyl 2.1 3.2 1.5Sulfonate S 3.3 2.4 0.8 Nonsulfonate S 0.4 0.1 Cl (organic) 16.0 12.24.2 7! Cl (inorganic) 2.8 1.6 3.9 1 Ca 0 O Na 1.5 1.0

Solubilities Diesel oil insoluble insoluble soluble in hot oil 5% NaOHsoluble soluble insoluble NaOH soluble soluble insoluble EXAMPLE IV Aresidual pulping liquor obtained from a kraft pulping process wasdiluted and neutralized with sulfuric acid to a pH of about 1,precipitating most of the lignin materials. The precipitate was filteredand washed with dilute sulfuric acid and water and dried. The recoveredlignin constituents had a diffusion coefficient of about 6.2 mm /day.

The recovered lignin constituents of the kraft liquor in an amount of150 g were dispersed in 500 ml of water and chlorine gas was slowlybubbled into the mixture at a temperature of about C. The chlorinationwas continued until about 74 g of chlorine had been absorbed. Thechlorinated lignin constituents were recovered by filtration, washedwith ether and dried. The above polymeric constituents were alkalinetreated by dissolving the product in a 10 percent sodium hydroxidesolution and maintained in the solution at about 80 C for 8 hours. Thealkaline treated mixture was then acidified to a pH below 1 withconcentrated hydrochloric acid to precipitate the polymericconstituents. The polymeric constituents were recovered from theacidified mixture by centrifuge and the product was washed with waterand dried. The polymeric constituents had a diffusion coefficient ofabout 7.8 mm /day.

The polymeric constituents thus obtained, in an amount of 50 g, weremixed with 40 g of fatty amine in about 400 ml of toluene. The reactionmixture was made slightly basic by the addition of 4 g of isopropylamic.The resulting mixture was then reacted in a bomb at a temperature ofabout 135 C overnight. Upon evaporation of the toluene and drying, 83 gof the lignin derivative was obtained.

The above derivative was tested as a water-in-oil emulsifier in themanner described in the examples above. About 1,200 ml of additionalbrine had to be added before inversion or coagulation of the emulsionwas obtained.

The analysis and the properties of the lignin constituents recoveredfrom the kraft liquor, the intermediate products obtained, and the finalproduct are shown in the table below.

Lignin Alkaline Material Chlorine Treated Lignin Isolated from OxidizedChlorine Oxi- Deriv- Kraft Liquor Product dized Product ative Analysis ZN 2.6 OMe 11.8 7.7 8.1 3.5 Z TotalS 2.1 1.4 1.2 0.7 Cl (organic) 10.5 00 0.4 Solubility Diesel oil (hot) insoluble insoluble insoluble mostlysoluble 5% aqueous NaOH soluble soluble soluble insoluble 10; aqueousNaOH soluble soluble soluble insoluble EXAMPLE V A nitrogen-containinglignin derivative was prepared from an air oxidized calcium base spentsulfite liquor.

A fermented calcium base spent sulfite liquor was used. To 28.5 kg ofthe liquor containing 10 kg of the spent sulfite liquor solids, 12.5 kgof a 50 percent sodium hydroxide solution was added. The mixture washeated to about 95 C in a steam-jacketed vessel and air blown into thevessel through a sparger at a rate of 13.9 cu ft/min for 19.5 hours.Water was added as necessary to maintain a constant liquid level. Thecarboxyl content, expressed as acid, of the oxidized product was 13.6percent, based upon the spent sulfite liquor solids. An ultravioletabsorption spectrum analysis of the oxidized product indicated that theproduct contained ultraviolet absorbing constituents, as lignosulfonicacid, in an amount of 46.3 percent of the solids.

To 13.6 kg of the oxidized product, a sulfuric acid solution containing50 percent sulfuric acid was added to acidify the mixture to a pH of3.5. The product was then heated to 50 C and 2.6 kg of a primary tallowamine was added. The product was heated with vigorous stirring until atemperature of C was reached, after which the mixture was allowed tocool at room temperature. The reaction product precipitated black incolor and granular in form. This precipitate was recovered in an amountof 4 kg by filtration through a 60-mesh screen. The product was airdried.

Various samples of the air dried amine salt were heated at about 165 Cfor various lengths of time. The products thus obtained were tested forsolubility in diesel oil and for emulsifying properties by determiningthe emulsion breakdown oltage. The emulsion breakdown voltage wasdetermined for the emulsion at two sodium hydroxide levels. The resultsobtained are shown below.

Diesel oil solubility was determined by suspending 5 g of a sample in150 ml of diesel oil in a weighed centrifuge bottle. The product wasthen heated in a water bath at C for 2 hours with occasional stirringand then cooled and centrifuged to settle the insolubles. The insolublematerial was washed twice with petroleum ether to remove all the dieseloil and then heated overnight at C to remove the petroleum ether priorto weighing.

Emulsion stability tests were made by measuring the emulsion breakdownvoltage of saturated salt brine water-in-oil emulsions prepared bystirring 3 g of the sample and 1 ml of 20 percent sodium hydroxide into40 ml of diesel oil for 5 minutes and then adding 30 ml of saturatedsalt brine. The mixing was continued for 30 minutes and then theemulsion breakdown voltage was measured with a Fann Emulsion Tester. Theemulsion stability test as described above was repeated except thatinstead of adding 1 ml of 20 weight percent sodium hydroxide solution, 5ml were added and the emulsion breakdown voltage determined.

EXAMPLE VI A nitrogen-containing lignin derivative was prepared from aresidual pulping liquor from a kraft pulping process without furtheroxidation of the liquor. The kraft pulping liquor had a carboxyl contentof about 12.2 percent expressed as acid radicals.

The polymeric constituents were precipitated from the kraft liquor,containing 30.6 percent solids, by acidifying the liquor to a pH ofabout 3.5 by addition of hydrochloric acid. The polymeric constituentsthus recovered represented 63 percent of the total kraft liquor solidsand had a carboxyl content of 10.3 percent.

About 20 g of the precipitated constituents were slurried in 240 g ofwater and 20 g of fatty acid amine added. The mixture was heated toabout 85 C and then cooled. The pH of the aqueous phase of the reactionmixture after the addition of the amine was 8.0. The reaction productwas recovered from the reaction mixture by filtration and heated in anoven at 145 C for 16 hours. Upon testing the heated product, an emulsionbreakdown voltage of 480 volts was obtained with the product for theemulsion stability test described in Example V for emulsions containing1 ml of sodium hydroxide and also 5 ml of hydroxide.

What is claimed is:

1. An oil base drilling fluid composition which comprises a continuousoil phase fluid containing in effective amounts as an emulsifier alignin derivative prepared by intermixing polymeric constituents of anoxidized lignin product with a primary or secondary amine havingsubstituents selected from the group consisting of alkyl radicals havingfrom six to 30 carbon atoms and phenyl radicals to form a salt, andheating the resulting salt of the amine and polymeric constituents at atemperature in the range of 120C to the thermal decomposition of theresulting product until a substantial portion of the resulting productis converted to a nitrogen-containing product wherein the nitrogen issubstantially stable in an aqueous alkaline medium at room temperature,said polymeric constituents being water-soluble constituents having adiffusion coefficient not greater than 25 mm /day, and said oxidizedlignin product having a carboxyl radical content, expressed as acidradicals, of at least 8 weight percent.

2. A composition according to claim 1 wherein said oxidized ligninproduct contains from 10 to 35 weight percent of carboxyl radicals,expressed as acid radicals, and the resulting reaction product is heatedat a temperature of 120 to 200 C.

3. A composition according to claim 2 wherein the oxidized ligninproduct is a residual pulping liquor obtained from a kraft pulpingprocess.

4. A composition according to claim 2 wherein the oxidized ligninproduct is an oxidized spent sulfite liquor.

5. An oil base drilling fluid composition which comprises a continuousoil phase fluid containing in efiective amounts as an emulsifier alignin derivative prepared by intermixing polymeric constituents of anoxidized lignin product with a primary or secondary amine havingsubstituents selected from the group consisting of alkyl radicals havingfrom six to 30 carbon atoms and phenyl radicals to form a salt, andheating at a pH of at least 4.5 the resulting salt of the amine andpolymeric constituents at a temperature of from C to the thermaldecomposition temperature of the reaction product until a substantialportion of the resulting product is converted to a nitrogen-containingproduct wherein the nitrogen is substantially stable in an aqueousalkaline medium at room temperature, said polymeric constituents beingwater-soluble constituents having a diffusion coefficient in the rangeof 8 to 20 mm /day, and said oxidized lignin product containing at least8 weight percent of carboxyl radicals, expressed as acid radicals.

6. A composition according to claim 5 wherein the oxidized ligninproduct is an oxidized spent sulfite liquor.

7. A composition according to claim 5 wherein the oxidized ligninproduct is a residual pulping liquor from the kraft pulping process.

8. A composition according to claim 6 wherein the amine is an alkylaminehaving from 10 to 20 carbon atoms.

9. A composition according to claim 7 wherein the amine is an alkylaminehaving from 10 to 20 carbon atoms.

10. A composition according to claim 8 wherein the resulting salt of thepolymeric constituents and the amine is heated under drying conditionsat a temperature of from 120 to 200 C at a pH in the range of 6 to 9.

11. A composition according to claim 8 wherein the resulting salt of thepolymeric constituents and amine is heated under drying conditions at atemperature In the range of to C for from one-half to 16 hours.

12. A composition according to claim 9 wherein the resulting salt of thepolymeric constituents and the amine is heated under drying conditionsat a temperature of from 120 to 200 C at a pH in the range of6 to 9.

13. A composition according to claim 9 wherein the resulting salt of thepolymeric constituents and the amine is heated under drying conditionsin the range of 145 to 185 C for from one-half to 16 hours at a pH inthe range of 6 to 9.

14. In a process of drilling a well the improvement which comprisescirculating in the well a drilling fluid composition of claim 4.

k i I

2. A composition according to claim 1 wherein said oxidized ligninproduct contains from 10 to 35 weight percent of carboxyl radicals,expressed as acid radicals, and the resulting reaction product is heatedat a temperature of 120* to 200* C.
 3. A composition according to claim2 wherein the oxidized lignin product is a residual pulping liquorobtained from a kraft pulping process.
 4. A composition according toclaim 2 wherein the oxidized lignin product is an oxidized spent sulfiteliquor.
 5. An oil base drilling fluid composition which comprises acontinuous oil phase fluid containing in effective amounts as anemulsifier a lignin derivative prepared by intermixing polymericconstituents of an oxidized lignin product with a primary or secondaryamine having substituents selected from the group consisting of alkylradicals having from six to 30 carbon atoms and phenyl radicals to forma salt, and heating at a pH of at least 4.5 the resulting salt of theamine and polymeric constituents at a temperature of from 120* C to thethermal decomposition temperature of the reaction product until asubstantial portion of the resulting product is converted to anitrogen-containing product wherein the nitrogen is substantially stablein an aqueous alkaline medium at room temperature, said polymericconstituents being water-soluble constituents having a diffusioncoefficient in the range of 8 to 20 mm2/day, and said oxidized ligninproduct containing at least 8 weight percent of carboxyl radicals,expressed as acid radicals.
 6. A composition according to claim 5wherein the oxidized lignin product is an oxidized spent sulfite liquor.7. A composition according to claim 5 wherein the oxidized ligninproduct is a residual pulping liquor from the kraft pulping process. 8.A composition according to claim 6 wherein the amine is an alkylaminehaving from 10 to 20 carbon atoms.
 9. A composition according to claim 7wherein the amine is an alkylamine having from 10 to 20 carbon atoms.10. A composition according to claim 8 wherein the resulting salt of thepolymeric constituents and the amine is heated under drying conditionsat a temperature of from 120* to 200* C at a pH in the range of 6 to 9.11. A composition according to claim 8 wherein the resulting salt of thepolymeric constituents and amine is heated under drying conditions at atemperature in the range of 145* to 185* C for from one-half to 16hours.
 12. A composition according to claim 9 wherein the resulting saltof the polymeric constituents and the amine is heated under dryingconditions at a temperature of from 120* to 200* C at a pH in the rangeof 6 to
 9. 13. A composition according to claim 9 wherein the resultingsalt of the polymeric constituents and the amine is heated under dryingconditions in the range of 145* to 185* C for from one-half to 16 hoursat a pH in the range of 6 to
 9. 14. In a process of drilling a well theimprovement which comprises circulating in the well a drilling fluidcomposition of claim 4.